I did that, the traceback says:
Traceback (most recent call last):
File "/private/var/mobile/Containers/Shared/AppGroup/979E2583-F740-4860-ACFA-8FDD0F71B319/File Provider Storage/111342185/local-storage/L3Byb2dyYW1pbmcvcHJvZ3JhbWFjacOzbi9wcm9ncmFtYXNfbmVyeS9jYWxjL2NhbGMucHk=/calc.py", line 2, in <module>
import matplotlib.pyplot as plt
File "/var/containers/Bundle/Application/3115F116-9E2E-4169-B4EB-3610A354BDDF/Pythonista3.app/Frameworks/Py3Kit.framework/pylib/site-packages/matplotlib/init.py", line 1050, in <module>
rcParams = rc_params()
File "/var/containers/Bundle/Application/3115F116-9E2E-4169-B4EB-3610A354BDDF/Pythonista3.app/Frameworks/Py3Kit.framework/pylib/site-packages/matplotlib/init.py", line 899, in rc_params
fname = matplotlib_fname()
File "/var/containers/Bundle/Application/3115F116-9E2E-4169-B4EB-3610A354BDDF/Pythonista3.app/Frameworks/Py3Kit.framework/pylib/site-packages/matplotlib/init.py", line 750, in matplotlib_fname
fname = os.path.join(os.getcwd(), 'matplotlibrc')
PermissionError: [Errno 1] Operation not permitted